The fabrication of organic light emitting diodes (OLEDs) is well known in the art. Typically, OLEDs are manufactured by depositing a plurality of electrically active polymer layers on top of a substrate with a first electrodexe2x80x94often ITO on top of glass. These various layers are processed in such a manner as to make a pattern of active pixel regions that are responsive to electrical signals addressing the pixels via column and row address lines in the case of a passive matrix display or alternatively via an active matrix thin-film-transistor (TFT) substrate with a common second electrode.
One of the major goals in manufacturing OLED displays is the reduction in manufacturing costs and the improvement of device reliability. Thus, the fewer processing steps or the least amount of time spent per step that are needed in their manufacture, the lower the cost. It is known in the manufacture of OLED displays that the step of patterning the polymer layers presents a particular set of problems. In many cases, the polymer layers are uniformly deposited over the whole substrate, for example, by spin-coating or evaporation techniques and the subsequent removal of the polymer layers over certain areas is required. It is known that some of these layers are very resistant to removal, for example, by ablation with a laserxe2x80x94making the resultant OLED display unreliable. Additionally, it is known that epoxy layersxe2x80x94that are often used to mechanically mate the OLED display with another piece of glass, metal or a foil to encapsulate the displayxe2x80x94do not adhere well if residual thin, (e.g. incompletely ablated) layers of polymer exist, intervening between the glass and the epoxy.
Thus, it is desirable to deposit the polymer layers precisely on the display initiallyxe2x80x94rather than lay such polymer layers down over the entire display area and rely on removal techniques to effectively pattern the display.
The present invention discloses a novel method for fabricating an OLED display wherein one or more conducting polymer layers is/are selectively deposited over the surface of the display. These one or more conducting polymer layers are kept away from areas where its presence is either not required for the resulting structure or is difficult to remove with usual techniques, such as laser ablation. Other polymer layers may be deposited uniformly over the surface of the display by way of spin coating or other suitable methods known in the art.
In general, a method for fabricating an organic light emitting diode display is disclosed, the steps of said method comprising:
depositing first electrode layer onto a substrate;
selectively depositing a conducting polymer layer onto said substrate with the first electrode layer wherein said conducting polymer is selectively deposited on the surface of said display such that said conducting polymer layer is not deposited in areas wherein said conducting polymer is not present in the final display;
depositing a semiconducting electro-luminescent polymer layer over said conducting polymer layer,
depositing a second electrode; and
encapsulating the device.